All lateral force apparatus known to have been put into field service have failed to achieve confidence in the application results. They apparently do not respond uniformly to the varied conditions encountered downhole.
By way of definition, stablilzers are not considered to be lateral force tools, although they certainly apply lateral forces to the well bore wall. Lateral force tools are considered to be those tools with active elements that move in order to apply more lateral force in one place than another about the well bore periphery.
The tool of this invention and tool of the copending application previously mentioned have been in experimental service and appear to perform as intended in the limited field trials to date.
Lateral force tools that respond to displacement of the drill string centerline from the well bore centerline to exert forces in selected transverse directions may be combined with conventional string stabilizers to yield various effects upon the drill bit. By combining the lateral force tool with one stabilizer arrangement, for instance, the drilling assembly will build angle in a deviated hole. The same tool may be combined with a different stabilizer arrangement under the same drilling conditions and drop angle. Such techniques are well known to those skilled in the art of directional drilling.
It is therefore an object of this invention to provide a well drilling tool that will produce a reactive lateral force between the drill string and a well bore wall to influence the course followed by a drilling assembly.
It is another object of this invention to provide well tools that provide lateral forces on drill strings that are proportional to drill string rotational rate.
It is yet another object of this invention to provide a well drilling tool capable of extending a lateral force element against a well bore wall that is somewhat overgage.
It is still another object of this invention to provide a drilling tool that will provide a lateral force on the drill string that is limited and proportional to drill string rotation rate.